I had this happen a lot back when I first got the car. Eventually I was able to replicated the issue on command with my wife in the car to justify the purchase of a new battery before it’s time.
I upgraded to a Group Size 78(r?) battery and it is significantly less pronounced, you can tell it does it a BIT but just a hair of stumble before it catches. Car hasn’t died or had an issue with it since and I’ve kept the same size battery going in and out of it on replacement.
I have had a theory that either the alternator tries kicking on to up the load and that nearly kills the engine or it is the torque converter as mentioned above.
